This invention relates to the general field of turbogenerator controls, and more particularly, to a command and control system and method for multiple turbogenerators in a grid parallel system.
A turbogenerator/motor can be utilized to provide electrical power for a wide range of utility, commercial and industrial applications. Since an individual turbogenerator/motor may only generate 24 to 50 kilowatts, there are, however, many industrial and commercial applications that require more power than is available from a single turbogenerator/motor. Powerplants of up to 500 kilowatts or even greater are possible by linking numerous turbogenerator/motors together. In any such application, multiple turbogenerators can be controlled and operated to provide total power (load following) or partial power (peak shaving or base loading).
There are two primary modes of operation for the multiple turbogenerator/motors linked together (commonly referred to as a Multi-Pac)xe2x80x94stand alone, where the turbogenerator system provides total power to a commercial or industrial application, and grid parallel, where the Multi-Pac synchronizes power to the utility grid and supplements power to the grid. The present invention is directed to a grid parallel system.
In the case of a grid parallel system, there are utility restrictions or variable rate schedules that govern the operation of the turbogenerator system. To maximize the economic feasibility of the turbogenerator, the system can be operated in the following control modes depending on the specific application and rate schedulesxe2x80x94(1) load following, where the total power consumption in a building or application is measured by a power meter, and the turbogenerator system equalizes or meets the demand, (2) peak shaving, where the total power consumption in a building or application is measured by a power meter, and the turbogenerator system reduces the utility consumption to a fixed load, thereby reducing the utility rate schedule and increasing the overall economic return of the turbogenerator, and (3) base load, where the turbogenerator system provides a fixed load and the utility supplements the load in a building or application. Each of these control modes require different control strategies to optimize the total operating efficiency, and all are addressed in the present invention.
When controlling multiple turbogenerator systems, a master controller is required to start, sequence, coordinate power commands, and provide fault handling to each of the individual turbogenerators. The specific control modes for the master controller are identified in this invention.
In most applications, a power meter that measures the load consumption (or production when a turbogenerator system is installed) in a building or application is also required. This power meter provides a reference or setpoint to the master controller for controlling the individual turbogenerators. If a building or application requires power, the master controller sequences the appropriate number of turbogenerators to meet the demand (or in the case of peak shaving, meet a user defined setpoint).
It is, therefore, the principal aspect of the present invention to provide a system and method to control the operation of multiple turbogenerators and associated electronic inverters.
It is another aspect of the present invention to provide a control system and method to control the flow of fuel into the individual combustors of the multiple turbogenerators.
It is another aspect of the present invention to provide a control system and method to control the temperature of the combustion process in the individual combustors of the multiple turbogenerators and the resulting turbine inlet and turbine exhaust temperatures.
It is another aspect of the present invention to provide a control system and method to control the rotational speed of the individual rotors of the multiple turbogenerators, upon which the centrifugal compressor wheels, the turbine wheels, the motor/generators, and the bearings are mounted.
It is another aspect of the present invention to provide a control system and method to control the torque produced by the individual power heads (turbine and compressor wheel mounted and supported by bearings on a common shaft) of the multiple turbogenerators and delivered to the motor/generators of the turbogenerators.
It is another aspect of the present invention to provide a control system and method to control the shaft power produced by the individual motor/generators of the multiple turbogenerators.
It is another aspect of the present invention to provide a control system and method to control the operation of the low frequency inverters which uses power from the direct current bus of the turbogenerator controllers to generate low frequency, three phase power.
It is another aspect of the present invention to provide a master control system to control the operation of two or more turbogenerators as a single system.
It is another aspect of the present invention to provide a master control system to maximize the overall efficiency of two or more turbogenerators in a single system.
It is another aspect of the present invention to provide a master control system to provide multiple modes of operationxe2x80x94load following, utility peak shaving, and base load, to optimize the economic investment return of the turbogenerator system.
It is another aspect of the present invention to provide a master control system to prevent repeated starting and stopping of the individual turbogenerator units by hysterisis bands, rate limiting and setpoint integration.
It is another aspect of the present invention to provide a master control system to reduce power transients of the individual turbogenerator units by rate limiting and setpoint integration.
It is another aspect of the present invention to provide a master control system to provide a fault tolerant system by responding to turbogenerator faults by dispatching other turbogenerators in the Multi-Pac.
It is another aspect of the present invention to provide a master control system that limits the start attempts of a failed turbogenerator system with a fault counter.
It is another aspect of the present invention to provide a master control system that balances the run time of each turbogenerator in the Multi-Pac, thereby extending the life of the total package.
It is another aspect of the present invention to provide a master control system that optimizes the transient response by running turbogenerators in idle or standby state.